Do not deprecate performed.

actionpack/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
+
 *   Add `config.action_view.logger` to configure logger for ActionView. *Rafael França*
 
 *   Deprecated ActionController::Integration in favour of ActionDispatch::Integration
@@ -33,8 +34,6 @@
 
 *   Deprecate method_missing handling for not found actions, use action_missing instead. *Carlos Antonio da Silva*
 
-*   Deprecate ActionController#performed?, check for response_body presence instead. *Carlos Antonio da Silva*
-
 *   Deprecate ActionController#rescue_action, ActionController#initialize_template_class, and ActionController#assign_shortcuts.
     These methods were not being used internally anymore and are going to be removed in Rails 4. *Carlos Antonio da Silva*
 

actionpack/lib/action_controller/metal.rb

@@ -186,6 +186,10 @@ def response_body=(val)
       super body
     end
 
+    def performed?
+      response_body
+    end
+
     def dispatch(name, request) #:nodoc:
       @_request = request
       @_env = request.env

actionpack/test/controller/base_test.rb

@@ -93,6 +93,12 @@ def setup
                               Submodule::ContainedNonEmptyController.new]
   end
 
+  def test_performed?
+    assert !@empty.performed?
+    @empty.response_body = ["sweet"]
+    assert @empty.performed?
+  end
+
   def test_action_methods
     @empty_controllers.each do |c|
       assert_equal Set.new, c.class.action_methods, "#{c.controller_path} should be empty!"